Application streaming is a technique in which a software application is downloaded from a server to a client on a network and executes on the client before the application has been completely downloaded to the client. As an alternative to the conventional ways of installing and executing software, application streaming has numerous benefits, including allowing centralized and streamlined application management and control, lowering application total cost of ownership (TCO), centralized license allocation management and compliance, reducing information technology (IT) operational expenses, improving service levels, and enabling software suppliers to distribute new capabilities for immediate use across an entire network.
U.S. Pat. No. 6,311,221 of Raz et al. (“Raz”), which is incorporated herein by reference, describes various methods of application streaming. As described by Raz, a computer application can be divided into a number of blocks. After a set of initial blocks are delivered to the client, the application begins to execute while additional blocks are streamed to the client in the background.
U.S. Pat. No. 6,574,618 of Eylon et al. (“Eylon”), which is also incorporated herein by reference, describes client-side software that can be used in conjunction with the techniques described in Raz to facilitate application streaming. As described by Eylon, a client system can be provided with streaming support software that establishes a virtual file system (“VFS”) on the client, operatively connected to the client's operating system, such that the VFS appears to be a local storage device. The VFS is accessed via a dedicated streaming file system driver (FSD) and is configured as a sparsely populated file system which appears to the operating system to contain the entire set of application files but, in practice, will typically contain only portions of selected files.
In the technique described by Eylon, all streamable files are stored in the VFS, at least partially; the remaining portions of such files are stored on the streaming server. Consequently, all streamable files are isolated from other (non-streamable) files in the client's file system. Other known application streaming techniques all require streamable files to be isolated from non-streamable files, restricting the streamable files to a special package, a VFS, or a predetermined portion of the client's file system at all times. This isolation provides more control over the streaming process at the client. However, it also undesirably prevents streamable applications and non-streamable applications from invoking or cooperating with each other; i.e., the isolation prevents “sharing” between streamable applications and non-streamable applications.
For example, assume a given client includes a non-streamable version of Microsoft Office in its file system and further includes a streamable version of Adobe Acrobat in its VFS. Using current known streaming technology, such as in Eylon, it is impossible in this situation for (non-streamable) Microsoft Office to invoke or otherwise cooperate with (streamable) Adobe Acrobat. For application streaming to become a complete alternative to the conventional way of executing software, it is important for such sharing of streamable applications to be possible.